Carbon is one of the important components of all organic materials and vital activities and, yet it is a nonmetal and has many advantages such that it has not only high conductivity of heat and electricity and small coefficient of thermal expansion but also strong stability against chemicals, so that it is utilized in many fields.
The carbon atom has four valence electrons and three or four hands (dangling bonds) which are not combined.
Moreover, carbon has been conventionally known as molecular, and allotropes which have four crystalline structures such as graphite, diamond, fullerene, and carbon nano-tubes have been known.
Specifically, since fullerene and carbon nano-tubes are fine and have characteristics such as large ion adsorption ability that conventional graphite does not have, they have been drawing attention as a new carbon material in the field of nano-carbons, studied in various fields, and put into practical use.
However, fullerenes and carbon nano-tubes are manufactured by heating and evaporating coke and a high polymer using, for instance, plasma, lasers, etc. Therefore, fullerenes and carbon nano-tubes are graphitized as a huge carbon allotrope where the covalent bonds made of six carbon atoms are included.
Each carbon material has only one ion adsorption ability, so that the ion adsorption ability of a fullerene composed of 60 carbon atoms is 60 at the most, and that of a nano-tube composed of 1000 carbon atoms is 1000 at the most.
Moreover, the oxidation compound is vaporized by applying heat-treatment to coke at 800° C. or higher and an allotrope of carbon can be obtained, but graphitization is accelerated and the coke hardens progressively.
Furthermore, it is known that hydrogen and oxygen are taken by sequentially cutting from the hand which has weak bonding when an organic material is heated, and it gradually changes (carbonized) to a material composed of only carbon. In Japan, “Charcoal” has been made since old times by carbonizing plants.